MIPS: make PCI_DMA_BUS_IS_PHYS=1 constant

No one of supported MIPS machines has an IOMMU unit, so we can safely define
PCI_DMA_BUS_IS_PHYS = 1. Also remove iommu flag from the pci controller
structure, since it is useless.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Cc: Linux MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/7604/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/pci.h b/arch/mips/include/asm/pci.h
index 8c16fb7..86b239d 100644
--- a/arch/mips/include/asm/pci.h
+++ b/arch/mips/include/asm/pci.h
@@ -43,8 +43,6 @@
 	   and XFree86. Eventually will be removed. */
 	unsigned int need_domain_info;
 
-	int iommu;
-
 	/* Optional access methods for reading/writing the bus number
 	   of the PCI controller */
 	int (*get_busno)(void);
@@ -106,11 +104,11 @@
 struct pci_dev;
 
 /*
- * The PCI address space does equal the physical memory address space.	The
- * networking and block device layers use this boolean for bounce buffer
- * decisions.  This is set if any hose does not have an IOMMU.
+ * The PCI address space does equal the physical memory address space.
+ * The networking and block device layers use this boolean for bounce
+ * buffer decisions.
  */
-extern unsigned int PCI_DMA_BUS_IS_PHYS;
+#define PCI_DMA_BUS_IS_PHYS     (1)
 
 #ifdef CONFIG_PCI_DOMAINS
 #define pci_domain_nr(bus) ((struct pci_controller *)(bus)->sysdata)->index